Swimmers in a swimming pool or an open body of water often use the front crawl stroke, where in order to breathe, a swimmer must either lift his or her head or rotate it to one side, which also rotates and disrupts the body alignment. While diving snorkels have long been used to permit divers to breathe when near the surface of the water without lifting their heads from the water, snorkels have only recently been developed to allow swimmers to breathe while using the front crawl or other strokes without lifting or turning their heads.
For example, a center-mount swimmer's snorkel patented under U.S. Design Patent no. Des 406,333 by Finis, Inc. has a snorkel tube positioned in front of the user's forehead and secured by a head-brace, which extends above the water surface and has at its lower end a mouthpiece held in the user's mouth and a water purge valve. One problem with the Finis, Inc. device however is that the user re-breathes their own exhaled air containing relatively high concentrations of carbon dioxide which causes dizziness and rapid breathing together with fatigue and head-aches.
Another problem with the Finis snorkel is that small amounts of accumulated water cannot be released because the water purge valve located below the mouth piece will not open during forceful exhalations due to the wide diameter of the breathing tube required for inhalation, and the water purge valve will only open when water has accumulated along the lower portion of the breathing tube up to the level of the mouthpiece, at which point an exhalation more forceful than normal combines with the downward pressure of the accumulated water to produce enough pressure to open the water purge valve to release most of the accumulated water. Thus the Finis swimming snorkel does not purge water effectively.
A side-mounted swimmer's snorkel is disclosed in U.S. Pat. No. 6,318,363 by Monnich. As in the Finis design, users re-breathe air remaining in the snorkel tube from the previous exhalation, resulting in dizziness and an increased pulse rate. Accumulated water in the breathing chamber can be released at any time by a forceful exhalation which triggers one-way adjustable flap-valves to close and block both breathing tubes, causing the water purge valve to open. The flap-valves need continued adjustment to close with the desired amount of pressure, and the water purge valve stays open during the entire forceful exhalation, releasing a large amount of air bubbles which produce noise and vibration. Another problem with the Finis snorkel is that the head brace is at a fixed angle relative to the mouthpiece tube, so it does not accommodate swimmers with differently shaped foreheads.
There is a need for a swimming snorkel for use in recreational and fitness training which prevents users from re-breathing their exhaled air, and allows easy purging of accumulated water.